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Tue, 04 Nov 2025 23:30:41 -0800 (PST) Date: Wed, 5 Nov 2025 08:30:38 +0100 From: Petr Mladek To: John Ogness Cc: Sherry Sun , "esben@geanix.com" , "senozhatsky@chromium.org" , "tglx@linutronix.de" , Greg KH , Jiri Slaby , Shawn Guo , Sascha Hauer , "ryotkkr98@gmail.com" , "kkartik@nvidia.com" , "fj6611ie@aa.jp.fujitsu.com" , Linux Kernel Mailing List , linux-serial , "imx@lists.linux.dev" , Pengutronix Kernel Team , "linux-pm@vger.kernel.org" Subject: Re: [BUG] Suspend failure with nbcon + pm_debug_messages (Linux 6.18-rc4) Message-ID: References: <87tszamcaz.fsf@jogness.linutronix.de> <87qzuem7bo.fsf@jogness.linutronix.de> <87bjlhz8pw.fsf@jogness.linutronix.de> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87bjlhz8pw.fsf@jogness.linutronix.de> On Wed 2025-11-05 00:25:55, John Ogness wrote: > Hi Sherry, > > On 2025-11-04, Sherry Sun wrote: > >> Thanks for confirming the fix. I will make an official post on LKML > >> with the patch today. Since the i.MX nbcon-driver is already > >> mainline, I will CC stable. I will CC you as well. > > > > I'll keep an eye on any fixes you send later and verify them if > > necessary. Hope this fix can be applied to the mainline and the stable > > tree ASAP. > > Even with this patch [1] I am able to reproduce the problem on one of my > test boards. I am using the following extra boot arguments: > > no_console_suspend loglevel=8 initcall_debug > > And then: > > # echo 1 > /sys/power/pm_debug_messages > # echo mem > /sys/power/state > > This generates a lot of output and leads to the same suspend > failure. This may be due to the out-of-tree nbcon-8250 driver I am > using, which introduces extra irq_work usage within the driver. Great catch! > Could you please try the above boot arguments with your i.MX board? > > I am wondering if blocking the queueing of irq_work during suspend > should be generally implemented rather than just printk avoiding it. It > also seems to only be a problem for ARM32 so perhaps it needs to be > addressed at the architecture level. IMHO, we could not _quietly_ block irq_work during the suspend a generic way. We would need to warn about it so that the callers are aware of it. Then the callers would need to explicitly block it to avoid the warning. I want to say that explicitly blocking the irq_work in printk() looks like the right way to go. I think that it would be needed anyway. Best Regards, Petr